> So it should be OK to sell hemlock or nightshade and other all-natural plant-based poisons?

Sure, why not? Especially the plant itself, I see little reason to regulate it any more than any other kind of plant. Maybe require good labeling is in place, but other than that why not?

If anything one would regulate cultivating it in the US due to it being an invasive species, and really shouldn't be grown in North America. But the cats out of the bag on that one, its already all over the place.